Parts such as the Seat / Step: Nut,hex.,8mm, Bolt,hex 8x20, Washer,plain,8mm, Bar,handle are included in the Z50a Mini Trail 1974 Z50ak5 Usa Seat / Step parts fiche.
The Pin,cotter 1.6x15 is the lowest priced item on this Seat / Step schematic.
On this parts fiche the Washer,plain,8mm is the most specified component.